


The Golden Siren

by Luna_guna13



Category: Fate/Grand Order
Genre: Alternate Universe - Siren, M/M, No Beta, Other Additional Tags to Be Added, Prince Arthur, Siren Gilgamesh, Slow Burn
Language: English
Status: In-Progress
Published: 2020-03-08
Updated: 2020-08-26
Packaged: 2021-02-28 17:27:04
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 4
Words: 12,743
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23070922
Author URL: https://archiveofourown.org/users/Luna_guna13/pseuds/Luna_guna13
Summary: Sirens are known for mercilessly devouring seamen and sailors, their bloodthirst was unstoppable, or so it was always said."  My name is Arthur..."" Ar-rrh...?" A soft gurgling sound was heard within the creature's throat." And you are...?"
Relationships: Gilgamesh | Archer/Arthur Pendragon | Saber
Comments: 49
Kudos: 107





	1. Chapter 1

**Author's Note:**

> Oh god...I didn't even finish my other multichapter fanfic...  
> Anyway, I've always wanted to write this so here we go!  
> ( Note : Arthur is 12 and Gil is 10, but that is only for the beginning of the fanfic, that will change soon dw. So right now they are Kid Gil and Arthur lily)

Arthur had just finished his daily training together with Merlin and was currently walking through the marketplace, his Mother's birthday was coming up soon, so the little boy decided to seek a gift for her.

He found countless dresses and accessories, but was never quite sure if his mother would truly enjoy it. 

The young prince continued to walk through the different stands and shops, but never found something truly satisfying.

Arthur has now searched every single stand without any success, he almost didn't want to inspect the last one, but reluctantly did it anyway.

"Oh my, your majesty are you searching for something special?" An old lady gently smiled at the boy, while placing a mug filled with tea on the counter.

" I'm searching for a birthday present for mother, but..." The little royal looked on the floor with sadness, he just wanted to get a gift for his mother, he didn't expect it to be that difficult.

" Hmm...A gift for the queen, huh?" The shopkeeper grabbed something from the drawers and placed it on top of the wooden counter, showcasing it to the young boy.

" A hairclip...?" Arthur gently grabbed the piece of jewelry and inspected it, it was beautiful. It was made out of gold and formed into a delicate branch, small detailed leaves were professionally attached to the clip, the object gently shined in the light, it reminded Arthur a lot of the pretty stars decorating the night sky.

" I'll take it!" The prince beamed at the lady with happiness, he finally found the perfect gift! The woman let out a chuckle at the boy's behavoir, before gently petting his head.

" You can have it for free..." Arthur was about to protest, before the women raised a finger, immediately silencing him. " Your parents have done a lot for the kingdom, take it as a small thanks for their hard work." 

She gave him a kind smile, at which the prince beamed before walking out of the shop with a loud  _ ' Thank you!'  _ and a small  _ ' Goodbye!' _

Arthur ran out of the shop with a satisfied grin, he finally found a gift but he was late for dinner and his parents must already starting to get worried. The prince ran across a bridge with the gift in hand, but failed to notice a black cat cleaning itself on the middle of the road, Arthur tried to doge in time, but unfortunately fell over the feline. 

" O-Ouch!" The blonde fell face first on to the floor, immediately losing his grip on the hairclip, the piece of jewelry fell off the bridge into the cold ocean water, with a small _ 'plop'. _

" No!!" Arthur looked to the cold water, before running down the small hill towards the beach, the small cat hissed at him while aggressively bearing its teeth.

"I'm sorry, I didn't mean to run over you!" The boy hastily said, before trying his best to not trip over the sharp rocks, which were scattered around the beach.

The prince eventually made it to the stony beach and tried his best to find the piece of jewelry, but the water was too aggressive for one to wade inside, which made the boy fall to the floor with a defeated sigh.

"...And the lady was kind enough to gift it to me, as well..." Arthur pouted, today was a disaster, he should at least go back to the old lady and pay her, so that her efforts were not in vain. The boy was about to stand up, until a wet hand hesitantly touched him.

" Eh?!" The blonde shrieked back at which the creature squawked back as well, with widened eyes filled with panic.

" You are a...S-Si..." Arthur slowly stood up and looked up and down the creature's body, which was now mostly hidden by the water, its head was the only thing that carefully peeked out of the deep ocean.

The creature had a human head with blonde hair and striking crimson eyes, but Arthur was more focused on the golden almost translucent fins, which acted like the boy's ears. There were also golden scales, scattered around his neck, which became less and less the closer one looked up his neck.

"...A siren..." The prince finished with a small whisper, he couldn't believe his eyes, he had only ever heard of sirens from stories and books. He also saw once the aftermath of a crew of sailors battling a group sirens, their wounds were stomach-turning and only a few shipmen survived the attack. Arthur was always told that they were extremely aggressive, hungry for human flesh and should be immediately killed off as soon as possible.

The siren lifted his hand out of the water and Arthur was about to draw his sword, until he spotted the beautiful hairclip resting on its palm.

The prince carefully stepped closer to the creature and looked at the piece of jewelry in awe, did the siren actually desire to help him or was this a trick to lure him in...?

Arthur glanced unto the face of the other and was surprised to see that the creature, no the siren was a boy just like him, appeared to be as young as him.

The siren curiously watched him with wide eyes, it seemed like that the other was as scared of him as Arthur was scared of him.

The prince carefully lifted his hand and reached for the golden object, the siren had small claws and a bracelet made out of seashells around his wrist, but everything else appeared human to Arthur. There was another translucent fin attached to his forearm and small scales surrounded it, the prince thought that they were very pretty, they shined as beautiful as the hairclip. As soon as Arthur held the hairclip in his hand, the siren immediately left, a small amount of saltwater hit the boy's face and he fell back unto the cold beach floor with a startled yelp.

" W-Wait!" Arthur tried to call out to the siren, but it was longer seeable, the deep ocean water hid it perfectly.

"...I wasn't even able to say thank you..." The boy bitterly muttered under his breath, while looking at the hairclip with a sad frown. He searched one more time through the thick waves of the sea, before turning around to return to the castle, his parents were probably already searching for him...

Unknown to the boy, the creature continued to curiously observe him, while staying hidden by the impressive rocks, which protruded out of the sea. The siren watched the boy before he disappeared behind a group of buildings and decided to return back to his home as well. 

\----

" Arthur dear, was there a reason for your late return?" His mother asked, while they sat at the dinner table.

" Merlin decided to prolong our training for a bit, that's all..." The prince horribly lied, but thanked God that his parents didn't notice it. They continued to eat in silence, the sound of the crackling fire echoed through the room and Arthur wondered if sirens were resistant against coldness, since they were able to survive the cold waters of Britain.

" Father...do you know anything about sirens?" Arthur tried to passively ask the question, since he didn't want to raise any suspicion. If word came out that a siren was sighted near the castle halls, then a hunt was most defiantly going to get organized to kill the  _ 'beast'.  _

The king gave him a questioning stare, before taking a large gulp from his wooden cup and finishing it with a satisfied smile.

" What is there to know? They are bloodthirsty creatures, my boy. They should be executed immediately..." He calmly stated, while cutting a piece of meat. 

" But could it be..." The prince looked down to his lap, before whispering quietly. "...that sirens can be friendly, too? " 

There were a few seconds of silence, before his father erupted in a burst of booming laughter even his mother chuckled quietly to herself.

" My boy, haven't you seen the wounds of the shipmen, especially the losses they had to endure? Sirens feed on us, so we naturally have to protect ourself from them, we are nothing but prey in their eyes." The King continued to laugh for a bit, before going back to eat the piece of steak.

" I guess that's true..." Arthur muttered to himself, before finishing his meal as well.

\----

It was the next day and the prince had finished his training, Arthur bid Merlin goodbye before immediately rushing to the same beach then yesterday.

The prince brought an extra piece of bread along and told Merlin, that his hunger had been growing for the past days, at which his trainer simply nodded before commencing with the next sword attacks.

Arthur impatiently waited on the beach for the next hour, nothing special happened and the blonde decided to call it a day, before he heard a small gurgle. The prince turned around just to face the siren, he had been excited to meet for the past hours. Arthur immediately ran towards it, an action that made the creature instantly back away with a hesitant bubbling sound.

"W-wait..." The royal slowly waved with hands, before continuing to slowly walk up to the siren. " I'm sorry, I didn't mean to scare you like that..." The other was once again only peeking out of the water with his head, his crimson eyes eyeing the prince carefully.

Arthur kneeled down at the edge of the water and gave the siren a small smile.

" I'm Arthur, nice to meet you!" He beamed at the other, while placing his hand on his chest, signaling what he meant with the name.

The siren slowly raised himself from the water and placed his upper body on a small rock, a small golden fin went down his back, the rest was still hidden by the dark water.

" Ar-rrh...?" The other tried to pronounce his name, but only a soft gurgling sound came out of his mouth.

" Yes, Arthur." The prince laughed a bit, before slowly repeating his name, at which the siren only moved his head to the side.

The blonde got something wrapped in paper out his leather bag, before slowly offering it to the other. The golden siren eyed the item and gave it a quick sniff, before hesitantly taking it off the other's hand. Their hands brushed at the action and Arthur had to let out a small gasp, the creature's skin was incredibly smooth, but a bit cold, which was no surprise with these waters. The siren unwrapped it and gave the prince a questionable stare.

" It's bread, something to eat." Arthur demonstrated the eating part, as he opened his mouth while pointing at it. The other gave him an understanding nod, before taking a small bite of the piece of loaf. Arthur noticed small fangs peeking out of the siren's mouth and wondered, how exactly it was possible to rip out chunks of meat with them, since they were still rather small. It was definitely not his age, he heard stories of young sirens still being able to rip off limbs from sailors and he was not going to test that theory anytime soon. 

Arthur looked up his form once more, the boy wasn't your typical siren either. He had golden scales and beautiful scarlet-red eyes, something which the prince has never heard of before. Sirens usually had ice-blue scales and long talons together with a row of sharp teeth, their eyes were usually painted in cold colors, like blue and grey.

" You're nothing like the stories..." Arthur muttered under his breath.

A loud hissing sound was heard and the royal looked up to see the other spitting out the piece of bread, while throwing the meal into the cold water.

" I guess you didn't like that..." He sheepishly scratched his neck, sirens were known for eating meat and fish, offering bread was probably a stupid idea...

The creature let out a huff, before raising himself even more out of the water and placing his entire body on top of the rock, which revealed his entire form.

"..." The prince widened his eyes, he had never seen anything so pretty before. A long golden tail replaced the legs of the siren, the scales shined as brightly as the hairclip, the luxurious scales faded into an innocent white at the end and a long translucent fin finished the look.

" So pretty..." Arthur gasped and was about to reach out for the tail, until an aggressive hiss brought him out of his trance. He looked up to the siren, which gave him an annoyed glare, while moving his tail with a huff.

"...Sorry I didn't mean to do that..." He apologized before thinking about the countless stories the sailors had told him, sirens didn't own golden scales nor golden fins, they usually had dark blue coverings which lightened up in the night time, giving the scales a paralyzing blue.

" Could it be that you're not from here...?" The prince muttered more to himself than to the other, before shifting into a more comfortable position.

" Do you have a name?" Arthur curiously asked him, before realizing that the other wasn't able to understand him.

" I'm Arthur..." He pointed to himself and then pointed at the other. " And you are...?" The siren swayed his fin from left to right and startled to let out small bubbly sounds.

" Grrghil..." 

" Gril..?" The creature deadpanned at him and gave him a _ ' are you kidding me look' _ , before trying to say his name again.

" Gggriiill..." His head moved to the side and that was the first time Arthur was able to see the small gills located at the siren's neck.

" Gil...?" The siren repeatedly flapped his tail up and down, while letting out a small grin, his small fangs becoming even more apparent.

" Gil, huh? " Arthur thought that it had a nice ring to it, he slowly reached his hand out to the other and gave him an excited smile.

" It's nice to meet you, Gil." The siren hesitantly grabbed his hand and got a bit startled when the young prince gently squeezed it.

"...Thank you for yesterday..." Gil wasn't able to speak the same language as Arthur, but understood it anyway, since he gave him a pleased huff together with a nod. The loud ringing sound of two bells was heard and the prince immediately shot up, turning around to look at the large clock tower. " It's already this late...?" Arthur pouted a bit, before giving Gil a small smile.

" I have to go now, but I'll come tomorrow again..." The young boy ran up the hill before adding "...with better food, of course!" The siren longingly watched the other's fading form before looking back into the water with a small whine, his form trembled a bit. He knew that it wasn't safe to stay on land, so he dived back into the cold waters, the darkness of the sea surrounded his vision.

\----

After the prince finished his dinner, he hastily excused himself before running into the library. Arthur wanted to know everything about sirens, so that it would be easier to understand his new friend. He had to smile a bit at the though, a siren as a friend... Something like that was unknown, but he saw no reason why not to befriend the other, since Gil would have already attacked him if he desired to eat him.

He found a few books, one was about the sea and its creatures, another was about the folk tales surrounding the British isles and the last one was about an encounter with a group of sirens.

Arthur checked if anyone patrolled the hallways, before running up to his room and hiding the books under his blanket with a satisfied huff.

He waited until most of the voices calmed down and opened the first page of a book, finding the drawing of an adult male siren.

The drawing was so much more different then Gil, the other siren had sharp claws, the fingers were connected with a thin web and he even owned gills on his waist. Gil only owned very small gills on his neck, additionally, the man's backfins had large barbs, which could easily cut through human skin.

" Just why are you so different...?" The young prince was determined to find out the cause of the lack of similarities, but immediately closed the book as soon as he heard a soft knock on his door. Arthur hastily put the blanket around his form and closed his eyes.

Quiet footsteps, which sounded like his mother, wandered to his bed, before he felt a gentle hand caressing his forehead with a small goodnight. The queen blew the candle on top of Arthur's table and softly closed the door behind her, at which the young prince let out a tired yawn. The training was a bit harsh today and he was more tired than usual, sleep sounded simply too welcoming.

_ ' I'm going to Gil tomorrow anyway...'  _ Just the thought excited the blonde, he also wondered for a second where exactly the other slept, Arthur was pretty sure that sirens didn't utilize beds or rooms...He simply hoped that the other slept somewhere safe and comfortable...


	2. Chapter 2

**Notes for the Chapter:**

> Thank you for your lovely comments everyone! <3

The young prince woke up earlier than usual, he wanted to explore the royal cuisine, to find anything that his siren friend would enjoy. Arthur found a few fresh sardines laying on top of a counter and glanced around in case of being spotted, the blonde stuffed them with one quick movement into his bag and immediately ran out of the kitchen.

A few servants and knights gave him questioning glances, but he simply ignored them, while hoping that he didn't act too suspicious.

Arthur made his way towards his trainer, Merlin and gave him a cheerful ' Good morning!'

" Good Morning, your Majesty! Did you have a good night's sleep?" The mage said in his usual cheerful attitude.

" I-I did...Good morning to you as well..." The prince was still unsure if he was good at hiding his secret, Merlin was incredibly hard to read and he always wore his trademark grin, which made it so hard to understand his trainer. 

They began with their usual training session, Arthur had to run for the next hour, which deemed as a form of warm-up and boosted his endurance at the same time. After that, they continued with sword lessons and simple weight lifting, the training was as merciless as ever, but the promised visit with Gil made it almost tolerable.

" Is there something on your mind, your majesty?" Merlin asked, while watching the other performing a set of jumping jacks.

"..." Arthur was a bit startled at the question and messed up his set, but decided to simply restart it.

"...Do you know anything about sirens?"

" Hmm..." Merlin placed his finger on top of his lips and gave the other a mischievous grin, at which Arthur simply glanced back unto the floor, could it be that the other knew his secret?

" You have to be more specific with that question, your majesty." More specific? The prince didn't really know where to start, there were so many things that he didn't understand or knew, but asking too many questions would probably raise suspicion, so he had to keep it simple.

"...Is it possible for a siren to understand a human?" The easiest way to receive some answers was to ask Gil himself, but he doubted that he would be able to ask any complicated questions with mere pointing and pantomime, if there was a way to communicate with the siren, then everything would be so much easier.

" I have never heard of a siren and a human holding a civil conversation, but they should be able to learn our language..." Merlin trailed off, while Arthur continued on with his next set of exercises.

" Their build is similar to humans, regarding their upper body area of course, and they are extremely clever creatures. If one had enough patience to teach one, then it should be able to master our language." Did that mean he had a chance to properly talk with Gil? But Merlin did add the 'patience' part and teaching a form of language the siren has never heard before, was most likely as time-consuming as teaching a toddler, but Arthur didn't mind. If he had a chance with actual conversations, then he was going to do his best.

" Why the sudden interest in sirens?" 

" It's nothing in particular..." The prince lied with a slight frown.

" I just saw a book about them and it raised my curiosity." Merlin gave him an understanding nod and stopped asking anymore questions, which made Arthur sigh with relief.

They continued the training session without any further questions and were already finished for the day, before Arthur had the chance to realize it. He packed his gear and additional items in the leather bag, before turning around to say goodbye.

" Bye Merlin, see you tomorrow." The prince excitedly turned around and walked with fast steps out of the training court, his thoughts were filled by Gil and he couldn't wait to 'talk' with the siren.

" Have a nice day your majesty and don't go swimming with sirens, now!" Merlin meant it as a joke, Arthur was fully aware of that, but it still made the royal uncomfortably tense.

" Heh..." He tried to laugh it off, before giving the other a small wave and slowly jogging towards the beach. The sky was dressed in its usual grey clouds, a ray of sunshine occasionally shined through them and got reflected rather nicely by the seawater.

" I wonder how Gil's scales would look like under the sun..." Arthur muttered under his breath, the golden scales were already so incredibly beautiful, he wondered how brightly they would shine under sunlight.

The prince finally made it to the spot of their secret meetings and placed his bag on top of the stony beach, while searching for anything golden hiding in the sea.

And within mere seconds a cheerful and familiar sound was heard, the golden siren appeared out of the water with a cheerful grin.

“Gil!” Arthur exclaimed with a smile, before rushing to the other and sitting across them.

“Argurr!” The siren said with a flip of his fin, at which the prince had to let out a gasp. Did the other just try to say his name? It definitely sounded like it and it made the blonde even more excited.

“ Let’s try again...” The prince pointed to himself with a small smile.

“ Ar-th-ur.” 

Gil intimidated his movements and hesitantly opened his mouth, before trying again. 

“ Arurr!” He had to chuckle a bit, it didn’t sound as bad anymore and Merlin seemed to be right, Sirens were indeed very fast learners! The prince grabbed the sardines out of the bag and handed it to the other.

“ This is food, like the bread. Just much yummier.” Gil eyed them even more suspicious, the bread tasted like rotten food to him, but his mouth watered with want as soon as he smelled the fresh sardines. 

Arthur held one fish by its tail and planned to hand it over, but was surprised to see the siren jump up with excitement and bitting the majority of it off.

“ I guess you like it...” The prince said a bit startled, while watching Gil happily chew on the raw delicacy.

He did the same with the other two and soon the siren idly floated in the water, a content smile decorating his face.

Arthur simply watched the entire time, he thought that the movement of the fin was fascinating and tried his beat to memorize every little twitch or elegant gesture.

After a while, a spontaneous idea popped up and Arthur gave the other a hand wave, to signalize the siren to come closer.

Gil tilted his head a bit, but swam closer nonetheless, to the point where he was able to sit right beside Arthur, it was a bit complicated to find a comfortable position, due to the siren never truly leaving the sea, but he was eventually able to find one together with the prince's help.

" Look...This is what you call a book." Arthur opened a small leather book which he used to read it a lot when he was younger, it was a picture book with colorful drawings, each page held a new and small story, about Britain and the world.

"...?" The young siren tilted his head at the countless pictures and letters, which looked like nonsense to him.

" Here, this is a Goldfinch. Its wings are golden just like your fin." Gil loomed over the page, the small bird reminded him of the animals which roamed the sky and the siren eagerly pointed towards them.

" Go...Golrrinch?" 

" Those are birds as well, but they are called seagulls." A form of wonder got displayed on the other's face and Arthur had to grin at the sight, before flipping to a page which would be better for studying.

" This is the letter A..." The prince pointed to the large capital, which was written with one elegant movement. " You pronounce it like this." Arthur proceeded with slowly vocalizing the letter and Gil joined soon after, it took a few tries, but soon the siren was able to do it without any problems.

" That was perfect!" The royal said, before continuing on with the next set of letters.

And after a few hours of pure studying and reading, Gil was able to identify the individual letters and assign a certain sound to them, it wasn't near perfect, but it was incredible how fast the siren was able to learn.

Perhaps the other would be able to read small words by himself? That thought alone made the prince huff in satisfaction, before he turned to the other with a grin.

" It's time for me to go, but I'll come tomorrow again..." Arthur was about to turn around and leave, until a cold hand stopped him. 

"...Is something wrong?"

" B...Book..." The prince let out a gasp, before kneeling down and grabbing both of the siren's hands, squeezing them with excitement.

" That was amazing, Gil! You were able to speak a word!" Arthur's eyes sparkled and the siren was a bit taken back at the compliment, before letting out a proud huff, while nodding his head with a pleased smile.

Arthur continued to smile, while holding the other's hands and noticed how they slightly shivered, he also saw the fin moving constantly, as if the siren was cold...

"...Are you cold, Gil?" The prince asked, the worry in his voice was rather obvious, but Gil didn't understand what the other meant, which was of course not his fault.

"...Here, I know that it won't be able to help you in the water..." The prince opened the cords of his cloak and placed it around the siren's trembling form. "...but maybe it will warm you up for a bit..." Arthur tied the two laces in a simple knot, while Gil simply watched in silence, the fabric felt weird to him, but not in a disturbing way. And soon an unknown warmth surrounded the siren, a warmth he wasn't used to at all, but slowly found himself cuddling into the soft cloth.

The prince remarked how the other stopped trembling and gave him a warm smile, but a form of uneasiness settled inside his gut. His friend swam day and night in those cold waters, Arthur always thought that sirens were resistant against the cold, but the sight in front of him proved the opposite. He gently raised his hand to touch Gil's cheek, silently making sure that the other didn't mind. The blond softly cupped the other's face and noticed with sadness, how cold the siren truly felt. 

The feeling became even worse as soon as Gil started to unconsciously lean into Arthur's warmth, a warm smile spread on his friend's lips.

The two church bells rang, their harsh notes echoed through the village and Arthur knew, that he should be already at home, sitting together with his parents on the dinner table, enjoying their feast, but...

Gil looked so incredibly _happy,_ the prince didn't find the heart to leave his friend yet, instead, he made himself comfortable and opened the book once more, while the siren sincerely enjoyed the welcoming warmth of the other and the cloak. The siren barely remembered the last time he felt such warmth before, the sea was always so cold and dark, he was barely able to see anything...But his friend was so _warm_ , just like home...

Gil's mood went for the worse at the thought of his old home, so he simply buried himself deeper into Arthur's warmth and gasped with happiness as he felt a warm arm wrap him in a cozy hug.

"...Want to look at more pictures?"

Gil glanced up and nodded with a grin, he still wasn't able to truly understand Arthur, but the other made it easy for him, to guess the meaning behind the blonde's words, so the siren was able to understand Arthur to some degree.

" This is a bluebell." The blonde turned to a page, with a very beautiful blue flower, a plant the siren has never seen before.

"...B..Bluebe..." He tried his best to use the knowledge, which he gained today, but the word was so _long_ and the siren decided to give up midway with a defeated pout.

" Yes, Bluebell..." Arthur chuckled a bit. " There are woods filled with these flowers, some people say that they give off a magical aura..." Arthur seemed to think for a bit, before adding with a hopeful smile. "...Maybe we can visit them someday..."

The pair continued to flip through the pages of the book, sometimes Gil would be so interested in one particular drawing that he constantly repeated the name of it, but Arthur wasn't annoyed by it, in all honesty, he found it quite cute.

They were so focused on the pictures, that Arthur lost track of time, he only glanced up to the clock with confusion as soon as a large shadow towered over them, due to nightfall making its way.

" Oh, no..." The prince whispered under his breath.

" Hmm...?" Gil hummed in curiosity and let out a small yawn, it seemed like he was quite tired as well.

" It's really late...I have to go now..." Arthur said with a small pout, an expression which the siren mirrored.

" But I'll come tomorrow...I promise..." He slowly raised himself off the floor and awkwardly glanced up the hill, he didn't feel right about leaving the other, but he was already gone for so long...His father would soon organize a search party and the prince feared, that there was a small chance for them to spot Gil and that could only end in chaos...

" Here..." Arthur gave the small book the other, a sad smile decorating his face. "...You won't be able to use it underwater, but I'm sure that you can hide it somewhere..." The prince slowly walked away, an uneasy feeling settled in his gut, a feeling which told him that he shouldn't just _leave_ , but what choice did he have? The feeling became so intense, that it made Arthur turn around and run towards Gil, the siren gave him a questioning glance and was about to vocalize his concerns, but halted midway, due to Arthur enfolding him in a tight, _proper_ hug.

" A...A-Arthur...?" 

" That was..." The prince whispered, embracing the other even tighter.

" That was the first time, you were able to say my name..." Gil hesitated a bit, before slowly clasping his hands around Arthur's form as well, he didn't quite understand the other's motive, but he treasured the hug regardless.

" Okay..." The prince slowly loosed his grip and stood up with an almost shy smile. "...Goodnight, Gil...See you tomorrow." 

"...N..Night, A-Arthur..." The siren said very slowly, his pronunciation was still a bit off, but it was amazing how much Gil learned in one day.

The prince waved him goodbye, before hastily jogging towards the castle.

The siren watched Arthur for a bit, before returning his attention to the book. The moon was in full bloom and there were barely any clouds, blocking its light. Gil continued to flip through the pages, remembering every single rule and letter Arthur taught him, he desired to study for a bit longer, so that Arthur would end up being very proud of him. He could already see the other's eyes sparkle with excitement as the siren professionally read out the words of the book. A cold gale made its way to the boy, it would have disturbed him wouldn't it be for his friend's cloak, shielding him from the coldness of the night. Gil happily rubbed his face against the silky material, it was foreign at first, but he absolutely adored it now, the cloak and the book also held a symbolic meaning to him...

They were both a gift from Arthur and he was going to treasure them, no matter what!

\-----

Arthur has never run so fast in his life before, the guards were about to close the main gate until they saw his advancing figure.

" Your majesty...! The King and Queen have been looking everywhere for you!" One of the guards exclaimed, while opening the heavy gate once more.

" I know...I know..." The prince said during rapid breaths. "...I'm going to them now..." Arthur gave the other knights a small hand movement before jogging towards the main halls, while silently thanking God for them not being able to find him and Gil.

He opened the main doors and was surprised to see both of his parents, drinking tea together with his mentor, Merlin.

" Father...Mother, I'm sorry for coming, too late. I swear it wo-." His father raised a hand, which immediately silenced him.

" It doesn't matter, I know that it won't happen again." 

"...?" He knows that it won't happen again...? What exactly was his father playing at?

" We have decided that you will no longer train here..." No longer train here...? Did that mean...

" Merlin and you are going to an island called Nemallia, there you will be able to perform even better and exceed at your royal responsibilities." Nemallia...? Arthur, of course, knew what that place was. The elite of the elite went there to train, it was an island full of challenges and only the best knights were allowed to train there, but... Normally Arthur would have been excited about such a thing, but now...

" I can't go...!" The prince exclaimed, he himself was surprised at the outburst.

"...My boy, I thought that you would be rather excited about that." He usually would have been, but...

What about Gil? He can't just leave his friend all alone, he wanted to talk so much more with the other, he can't just abandon him now, he _promised_ to-.

" The ship will leave tomorrow early morning, I will wake you then..." The King trailed off, a slight frown made its way unto his face.

" Now...It is rather late, it's best for all of us to sleep now." All three of them left, wishing each other goodbye, but Arthur stood still, he still couldn't believe it...

" I wanted to do so many more things with you..." The young prince muttered, sadness was clear in his voice and the boy felt his eyes sting.

"...I'm so sorry..." Small tears ran down his face, he didn’t know what to do anymore...an inner turmoil has built itself and the prince only cried in silence...

\----

It was the next day and the siren happily waited for the other, he even studied a lot today, just so he could demonstrate it to Arthur.

But...His friend didn't appear, maybe he was coming a bit later? The siren continued to wait, but no one came that day...And so, Gil patiently waited for the next day as well, but his dearest friend never returned. He even tried to call out his name a few times, but was met with silence and loneliness. The only thing which proved their friendship ever existed, was his warm cloak and the small picture book, the golden siren made sure to treasure them and his memories for all eternity.

**Notes for the Chapter:**

> Hope you enjoyed it... :)


	3. Chapter 3

**Notes for the Chapter:**

> I'm back ;w; !

Arthur has finally finished his harsh training, he excelled with flying colors, but that didn't mean it was easy, no far from that. For the past 10 years, every day has been exhausting, leaving no room for leisure or idle quarrel, but the prince never gave up nor slowed down. He craved to become the best, not to show off or for his reputation no...Arthur wanted to protect his people and his country, the only way to achieve this, was to become even stronger and smarter. So the little prince, who was not so little anymore focused purely on his training and finished sooner than expected, gaining the opportunity to finally return to the mainland and reunite with his parents.

Arthur was currently packing his personal belongings in a sac, which weren't a lot of things in the first place. The island provided the knights with their own clothes and resources. They were taught a set of skills as well, which even included cooking, so the blonde was not only good in combat and swordsmanship, he also owned an unusual insight in cooking. Naturally, Arthur was taught how to behave as a prince and learned the various responsibilities he should own, as a soon to be king. He, of course, paid close attention to those as well, but preferred the training sessions a tad more.

" Are you ready, your Majesty?" A rather timid voice chimed behind him and Arthur turned around to face a young knight in training opening the wooden door with a small ' _creak_ ', a shy smile decorating his features.

" I am, is the ship ready?" 

" Indeed it is." The blonde gave the knight a thankful nod, before hoisting the bag on top of his shoulder and walking with the other towards the shore. He gave the familiar structures once last glance, the training ground, the archery place, and the countless weapons neatly organized with care and pride.

He will definitely treasure the experiences and lessons he had learned throughout his training and put them to good use, finishing the harsh training didn't mean that he was going to slack off or become slothful. Arthur was going to try even harder, improve even more, to a point where he was positive, that he would be able to protect Britain.

They stopped in front of a small, wooden ship. A man, who was probably around his thirties gave the pair a short wave, his elegant clothing indicated his Nobel status, but the prince has never seen the man before...

 _'Perhaps his family regained more power over the years...?'_ Which would explain the reason for his appearance, Arthur didn't judge anyone by how poor or rich they were, he just thought it was a bit weird.

" Good morning, your majesty." The man gave him a respectful bow, which Arthur humbly accepted. " It seems that you have grown into quite the fine man!" He patted the prince's shoulder rather roughly with a slight chuckle, while the blonde gave him an uncomfortable smile. The man seemed to notice the discomfort of the other, since he backed down with a slight cough, before sheepishly scratching his neck.

" I apologize for my rash behavior, my name is Frewyn, a member of the Graves family."

'Graves...family?' He went over the appearance of the other once more, the man was as tall as him, but scrawnier, he had short brown hair and grey eyes, nothing screamed familiar nor well known. It shouldn't feel so out of place, but it did and something within Arthur advised him to keep a closer eye unto the other, which he was definitely going to do.

" Well, shall we start with our journey then?" Frewyn's voice awakened the prince from his thoughts and he gave the young knight a small goodbye, before joining the noble on the ship. He was alone with the other as well since Merlin already traveled to the mainland a few weeks ago, the mage apparently had some business to attend to, where he wasn't allowed to miss.

" There is a room in the back, together with a bed. In case you wish to rest, your highness." 

" Thank you for your kindness, but I'm fine for now." Frewyn simply nodded in silence and started to raise the anchor of the seafloor, while Arthur decided to unpack his notebook out of his bag. Merlin advised him, at the start of his journey, to start a journal, documenting his newly learned lessons and tricks, it was tiring at first, but turned out to be a nice stress reliever especially after an exhausting day of training.

The ship began to move and time passed faster than the prince expected, it was now late into the night and Arthur happily retreated to the small bedroom. 

The sea was tranquil and quiet, the day wasn't exhausting, far from it. He was just rather excited to see his old friends and parents again, the adrenaline had died down during the course of the day and made the prince realize how long he had stayed awake. It was in his best interest to at least rest his eyes for a bit, since he wanted to look presentable to his parents and his people. Even if Frewyn was on the suspicious side, he was trained to be a light sleeper, in case someone tried to physically attack him during his slumber.

Arthur was about to fall asleep, until a ghastly stench invaded his noses, it almost smelt like something was _burning_ . The prince tried to hastily raise himself off the bed, but a sudden wave of heat blasted into his direction, setting everything ablaze. Black smoke appeared from the flames and Arthur tried to open the door, but found it not _moving one bit._

 _'Don't tell me..!'_ He tried once more to forcefully open it, but it didn't budge, indicating that something was blocking its path. 

This was extremely _bad_ , he was trapped and the fire started to grow at an alarming rate, there were no windows to escape from either...

The heat and smoke began to become unbearable, the flames on the walls started to grow in size, too. He wasn't even able to see his own hands anymore, the enclosed room trapped him and the smoke together, diminishing his sense of vision. 

Arthur slowly felt his consciousness slipping, his knees grew weak and his lungs burnt with anguish. He fell to his knees with a hoarse noise, his body slowly giving up, with every desperate attempt of taking a breath more smoke filled his lungs, he tried to shield his mouth with his hand, but his attempts were futile, the smoke was far too thick and aggressive.

Even if his body was giving up, his mind certainly wasn't. He was not going to die because of something like _this._ The prince recalled that the walls of the room were rather thin and the fire must have weakened them even further, so he simply had to muster enough strength to break the walls, but he had to do it _fast_. The walls were the area where the fire came from in the first place, so acting too slow could easily conclude with him going up into flames, but that would anyway be his end if he continued to stay put.

Arthur slowly crawled to the nearest wall, every muscle aching with pain, his vision almost non-existent. He finally managed to reach the wall and sat into an upright position, the heat of the flames burned his skin, but he raised his arm regardless and struck against the glowing wall with his elbow. There was a cracking sound and a few splinters fell into the sea, but the opening was not big enough, so he mustered all the energy he still had and threw his entire weight against the wall, destroying the burning wood and falling with it into the cold ocean water. 

Arthur didn't even truly feel the coldness of it, his body still buzzed from the agonizing heat and his mind was slowly stopping to function as well, he felt how he slowly sunk to the bottom of the ocean, the water was crystal clear and tranquil, the opposite of the raging fire Arthur escaped from. 

The prince desperately tried to swim up, but he didn't sense his body moving one bit, it went stiff and rigid like a corpse. Instead of smoke, seawater was starting to invade his lungs, but he no longer had the energy to defend himself against it and his eyes slowly closed against his will.

The last thing he felt was a gentle, yet chilly hand touching his cheek.

The gesture reminded him of the times, when his mother lovingly put him to sleep, warmly wishing him goodnight...

\----

Arthur felt a warm light shining unto his eyelids and attempted to slowly open them, trying his best to get used to the illuminating sun. 

There was a black dot blocking the direct light of it, no more like a...person? 

"...?" His eyes were still full of salt and the person was barely distinguishable, but what Arthur was able to see was gold and _a lot of_ it.

The sky was gold, due to the rising sun and the stranger had...golden hair? It at least seemed to be the case, the more he blinked, the clearer his vision became and he found out that the person had indeed golden hair and crimson-red eyes. 

He was extremely...pretty and Arthur almost thought that an angel had saved him, until he saw translucent fins poking out on the side of the person's head...wait. Golden fins...golden hair and red eyes? There is only one being that had such characteristics!

" Gil...!"

The prince was about to happily hug him, until the siren reached out and hit him right across the face, immediately knocking the already weakened human out.

\----

" Your majesty!" The panicked voice of someone made Arthur shot up once again and he hastily tried to stand up, just to fall unto his knees again, since his body wasn't even near its full strength. 

" Oh god!" The stranger, who turned out to be a woman helped him up and gave him a worried glance, but he didn't give her any attention, because...he was positive that he saw his friend saving him, not just any friend. His childhood friend, which he adored 'speaking' to even if they knew each other only for a short period of time, Arthur has grown rather fond of the other. But...his training was so long and intense, it made it seem like their meetings were just part of the prince's imagination, since they looked so surreal, but he never forgot them. He was able to recall every single minute of them and seeing the siren once more, assured Arthur that they were, in fact, very real.

The blonde looked around and saw that they were on top of a beach, not where they always used to meet, it was far closer to the castle grounds and he saw that there was a path heavily engraved into the sand from where he stood, leading to the ocean.

" So he did drag me to shore..." 

" Your majesty...is everything alright?" He glanced a bit perplexed towards the woman, completely forgetting that she was standing beside him.

" I'm fine..." He glanced towards the sea once more, before adding. "...Did you see anything...odd?" 

" Odd...? Well, seeing you sprawled unconsciously on the sand was rather scary _and_ odd, but nothing else seemed to be out of the ordinary." The woman looked up his form once more, worried about the prince's weird behavior, thinking that he had probably hit his head somewhere.

" I also called for guards and a doctor, seeing that you have rather painful injuries."

Arthur gave her a thankful nod and already saw the group of men hastily running towards them, one of them was even his mentor, Merlin.

The mage ran up to the prince and quickly inspected his wounds, before letting out a tired sigh.

" These look pretty bad, where you burnt alive or something...?" It was meant to be a joke, but the prince was surprised by how accurate the question was.

" Are you able to heal them?" 

" Of course, I am your court mage for a reason! But let us first go to your parents..." Arthur gave him an agreeing nod and wanted to turn towards the woman to thank her, but found her already gone...

Additionally, he noticed that there was no way of recognizing that he was the crown prince, since he was away for 10 years and his appearance has changed a lot. The only people who knew him, were Merlin and a few knights on top of the island, but that was it. The lady shouldn't have known and she was gone now, too...Things were slowly starting to get out of hand and he doubted that the fire, was any form of accident...

" Your Majesty...?" Merlin gave him an odd look, the guards around them started to grow even more worried.

" It's fine, we'll discuss it together with my parents."

\----

He was welcomed by the guards with high regard and the heavy doors to the throne room, were opened with enthusiasm. His parents were both staring at the door with excitement and happily ran to their son, who they haven't seen for years, but stopped as soon as they saw his injuries.

" Arthur?! What happened...?" 

" The ship caught on fire..." He trailed off, which made Merlin frown for a bit.

"...But I don't think that it was an accident."

" You mean...someone tried to kill you?" His father asked appalled.

" I'm not sure, but the noble Frewyn acted a bit stran-."

" Frewyn?" His mother gave him a disbelieving look. " That can't be, he has helped us so much over the years...Are you sure it was him?" The way his mother stared at him made him feel even more unsure about the situation, he had no real evidence but...

" You're right..." His mother looked like she was ready to defend the noble at any moment and it made the prince back off with his accusation, he didn't wish to fight with his parents right after their reunion.

" I should rest, I probably inhaled too much smoke..." He turned around and walked towards his room, his parents giving his fading figure worried stares.

" Your Majesty!" Arthur heard the approaching voice of Merlin and found the mage running towards him as he slowly opened his bedroom door.

"Merlin...?" Oh, right he still had his injuries on him, he was probably there to heal them. He quickly undressed, except for his pants and sat on top of the large bed with a sigh.

Merlin went ahead and used his magic to heal his wounds, a purple light enveloped the mage's hands as he gently pressed them against the prince's wounds. The injuries soon started to fade, the pain slowly diminishing, until there were only a few scars left. 

To this day, Arthur found it fascinating how talented Merlin was as a mage, he knew no one who was better and he knew that he could trust the court mage with his life.

" Frewyn was found washed ashore a few hours before you, he claimed that the boat suddenly caught on fire, he suspects that an oil lantern must have caused it. " Merlin stood up and slowly walked to the door, before adding quietly. "...Your parents didn't know, the guards first told them about the accident after your reunion."

Arthur watched him close the door and let his back fall on top of the bed, the mattress felt unnatural to him, since he was used to the harsh beds of the island, the softness of it made him feel even more out of place.

" An oil lantern...?" He tiredly muttered under his breath, perhaps it was all a coincidence? Maybe he was being too sensitive, but then why didn't the guards say anything...? Shouldn't they have rushed to his parents as soon as the found out that his boat had sunk? But...his parents were completely convinced about Frewyn's innocence...and maybe the guards were too afraid to report him missing?

And then there was also Gil, the young siren who saved him. 

The thought made the prince wonder how old his friend truly was, perhaps sirens aged faster or slower than humans? He wasn't quite sure, he stopped researching about them as soon as he started with his training...Maybe, just maybe he had a chance with meeting Gil once more, although the siren didn't seem too fond of him, the other pretty much slapped him across the face, which wasn't even close to the warm welcome he expected. 

But for now...He should rest, it was in his best interest or else he might truly start to accuse the wrong people.

\----

It was a new day and Arthur decided to test his luck, he didn't bring anything in particular except for one thick cloak, large enough to cover his entire form. His welcoming ceremony would be held later that day and he wanted to freely walk around the kingdom, without attracting too much attention, even if only a few individuals knew his appearance, walking around with his royal clothing would easily expose him. 

On the island, everyone wore the same uniform, regardless if they were royalty or a commoner, but it was something Arthur had to get used to and he was fully aware of that.

Walking down the stone path awoke some memories in Arthur, especially as soon as he faced the bridge where he tripped over the black cat, the incidence which started the encounter with Gil in the first place.

The prince carefully hiked down the hill and jumped on top of the stony beach, with the cold wind blowing onto his face.

The water was in the same state Arthur remembered in it, dark and energetic, and as he expected it, nothing golden caught his eyes. 

" You really are far more stupid than I originally thought." A haughty voice made the prince look towards his right, where the siren was idly sitting on top of a rock. Arthur blinked his eyes a bit, before cracking a smile. 

"...And you have a talent for dramatic entrances, huh?" Gil seemed to be taken back by the playful response and simply continued to sit on top of the rock, his tail swishing from left to right. The moment of silence gave Arthur the time to inspect the other's appearance better, his form was lithe and he obviously grew taller, but everything else remained just as breathtaking as he remembered. But there was one thing, which was not the same _at all_...

" You are able to talk...." He exclaimed with fascination, at which the siren simply scoffed.

" Of course I am, your language is on the p-primitive side after all..." It was supposed to be a snotty remark, but Gil's face started to redden bit with embarrassment, as soon as he failed to properly pronounce the word 'primitive', which made Arthur let out a chuckle.

" Perhaps it is, even so, you're amazing, Gil." The praise made the siren let out a huff. " Of course, I am! I a-." He was cut off as soon as a third familiar voice chimed, calling after Arthur.

" Merlin?" The prince glanced towards the approaching figure with horror and turned around to warn the siren, but found him already gone.

"...Is something wrong, your Majesty?" 

"...No don't worry about it." He gave his mentor a smile and slowly headed up the hill, trying to lure the other away from Gil, just in case Merlin was able to sense him, since his magic was truly not meant to be underestimated.

" We still need you for a few preparations, regarding the ceremony."

" I see, then let us head back." He gave the other another smile, but his mind was still filled with the siren, so many questions popped up in his mind and he couldn't wait to ask them by their next meeting, surely Gil was somewhat interested in him as well, since he came to talk to him. Perhaps, they could return to their old habit of meeting each other daily, the thought sounded quite nice to Arthur and a small smile made itself on his lips.

**Notes for the Chapter:**

> Hope you enjoyed it!  
> Stay safe and healthy everyone! <3


	4. Chapter 4

**Notes for the Chapter:**

> Yes this story still exists lol

The sea was cold it always was, the temperature became even worse the deeper one traveled. Gilgamesh had no other choice but to sleep somewhere near the surface, which was extremely risky and could lead to his death anytime. Humans were dangerous without a doubt, he would be immediately killed as soon as one spotted him, but his main concern wasn't the humans...It was the _sirens_.

Unlike them he didn't own razor-sharp teeth and lethal claws, no. It was like comparing a shark to a fish, he had no chance against them. They would instantly rip him into pieces, showing no compassion, and if there was one thing he learned during his endless exploring and swimming, it was that sirens were the _cruelest_ creatures out there.

They wouldn't hesitate to murder their own kind...he learned that the hard way. 

Sirens may swim in groups, but held no interest for one another, they were selfish creatures and only hunted for themselves, children were no exceptions. Only the strongest survived and the weak would perish..it was a depthless system in his opinion, but he could hardly change it now, could he? Besides, he doubted sirens had the brain capacity to negotiate anyway.

" Hmph..." Gilgamesh quickened his pace, his long fin skillfully moved through the water, while crimson eyes kept watch of their surroundings.

It was highly unlikely to meet sirens so close to shore, they tended to linger in the deeper parts of the ocean, but one could never be careful enough. Especially considering that a full moon was approaching, the most dangerous time to be lurking in the waters. 

The full moon somehow managed to heighten the senses of _all_ creatures, may it be a siren, a nymph, or a fae.

For some, it only mildly strengthened their magical abilities...for others, it increased the urge to _feed_ , causing most predators to go ballistic to the point where anything edible was attacked.

Fortunately enough, the gruesome event didn't affect him _that_ much, sure it sharpened his instincts, but those were easy to repress in the first place.

Unlike the other sirens, he actually knew what self-control was.

Superior mind-game or not, his brain won't be able to defend him from a herd of hungry sirens he had to quicken his pace or else it might as well be his last evening swim.

Through the dark water, Gilgamesh vaguely spotted the underwater tunnel and gave his fin one last powerful flick, reaching it in one movement.

Just as expected the entrance sealed itself with a powerful rune and the blonde could return to an idle pace, death was no longer a concern of his...at least, for now, Enkidu would have warned him otherwise.

The further he swam into the tunnel, the sweeter the water became. It wasn't unpleasant just _different_ , he's been residing in the chilly waters of the sea for the past twenty years. He doubted he will ever adapt to freshwater, regardless of how often he used it as a shelter. The sweet taste simply didn't suit his tongue, which was a shame since large lakes would be safer and _warmer_.

Then again, a lake was an enclosed area, a perfect hunting ground for humans and a confined space had a limited food supply, who knew when it would run out?

A soft light at the end of the tunnel broke the surface of the water, illuminating the cavern in an aquatic blue.

As the siren finally reached the end of the tube, Gilgamesh glanced up the impressive shaft and silently gasped, the sight was as breathtaking as ever. The water was tranquil and clear nothing blocked crimson eyes from admiring the beauty of the surface. The golden rays of the setting sun shimmered through the elegant lily pads and out of the corner of his eye Gilgamesh spotted a small group of fish idly swimming in the shadows of the water-plants.

He wasn't easy to impress, but he had to admit. Enkidu truly gave it their all when they created the "pond". It was large enough for him to rest in, the limited space might become uncomfortable after a few days, but he only sought shelter for one night anyway.

The siren felt the water waver slightly and squinted his eyes at the rippling waves, identifying two slender feet carelessly playing with the water, causing his heart to stop for a second.

Why would a human play in a random pond, inside of an enchanted forest _now_ out of all times? It's not like this area was known for being particularly safe, the forest emitted waves of mana to _prevent_ people from entering. He didn't interact with humans very often, with no one except Arthur to be exact, but even he knew that humans stayed away from anything they didn't understand, which included this forest.

Besides, every time a full moon approached, humans tended to panic like wild animals which was rather ironic, considering the event only affected actual creatures. 

So the individual, who rudely splashed in his pond was either suicidal or mad.

Gilgamesh vaguely debated about scaring the stranger off, but realized upon closer inspection, that a light shimmer surrounded the legs, making them seem transparent. 

" That idiot..." The siren angrily huffed and swam up the shaft, pushing some of the plants away in the process.

" Enkidu...!" The blonde snarled as he breached the surface of the water, startling his ' _friend_ '.

" H-Huh?" Enkidu yelped while aimlessly waving their arms in the air, trying their best to stabilize themselves, somehow managing not to fall into the pond.

" Did you have to shapeshift into a human form?!" 

" Oh..." Enkidu sighed and glanced at their form with a laugh.

" I thought it would be funny." Their grin was the definition of; _backstabbing bastard,_ but it was Enkidu, the creature who loved to tease him at any opportunity...he should have expected it.

" Very funny." The other rolled their eyes before changing back into their spirit form, blending perfectly into the environment.

Normally, it wouldn't be possible for him to sense Enkidu's presence they were a forest spirit, an invisible creature that protected the earth and its inhabitants. They could reveal themselves by shifting into different species but were otherwise left undetected. 

Now, Gilgamesh was used to the small shift of mana in the air and could detect Enkidu, regardless of their form.

" What's gotten you so uptight? Did your little prince find a new siren to talk to?"

" Hmph, don't be ridiculous. He wouldn't dare to betray me for another." The siren scoffed and glanced to the side with a frown.

" He isn't very small anymore either..."

" Heh, I know." Enkidu lightly chuckled, causing Gilgamesh's scowl to deepen.

" What do you mean you know?" 

" I was there when you brought him to shore~." The spirit happily sang.

" W-What?!" 

How was that even possible?! He made sure to pay attention to his surroundings...or perhaps he didn't. Honestly, the event was rather blurry in his head, his instinct must have taken over at one point.

" But really, Gil...Slapping your own mate? That's not very charming." The siren flinched at the other's tease, before leaning his back against the edge of the pond.

" Shut it...besides he isn't my mate." 

" Is that so. _"_ Gilgamesh could _hear_ the smirk in his friend's voice and he would have definitely leaped at them if they weren't in their spirit form.

" It's not my fault!" He crossed his arms over his chest, violently moving his fin from left to right.

" That _mongrel_ was the one, who started the ritual." 

" And you're the one, who _accepted_ it." Enkidu dryly replied, causing him to click his tongue in exasperation.

" It doesn't _matter_ , he's a human. They don't have mates." The forest spirit hummed lightly, before whispering:" The full moon is rising, I have a feeling it won't be a gentle one."

Gilgamesh glanced up the sky, a soft breeze drifted through the forest, shaking the leaves of the trees. The first stars started to show their light and a distant howl broke the silence, sending a chilly shiver down his back. The first predators were awakening and he didn't even want to imagine in what state the sea was. 

The most aggressive sirens were most likely already hunting, utilizing their songs as a lure, tricking the unfortunate beings which were close enough to hear it.

He just hoped that Arthur wasn't anywhere near the shore, knowing him the royal would look for Gilgamesh just to _talk_ , regardless of it being a full moon. Hopefully, there was someone actually _sane_ in Arthur's vicinity, preventing him from doing anything dumb.

A soft grumble interrupted his thoughts and the blonde noticed with a scowl that it was his stomach, which emitted the embarrassing sound.

He could repress his instincts, but not his hunger, and Enkidu softly laughed at his foul expression.

" There is a small group of fish in the pond." The water softly moved, indicating that Enkidu was touching it.

" It should be easy to hunt them, go and have your fun."

With a huff, Gilgamesh dove into the depths of the cave, searching for anything edible.

\---

" This full-moon is rather intense."

Arthur placed the book on the table, glancing at his mentor with a frown.

Merlin had been acting weird for the past hours, he didn't think much of it at first, after all, Merlin wasn't very normal in the first place. But even for him, his behavior had been rather...worrying, to say the least. The court mage had been constantly looking out of the window, deliberately searching for something until finally...the moon rose. 

His teacher stopped aimlessly pacing around and proceeded to stare at the moon, not even blinking once, before finally seating himself beside Arthur. 

" Is there something unusual about tonight?" The prince tiredly asked.

He was well aware of the fact, that the moonlight affected the creatures of Britain, the large walls around every city were built for a _reason._

" The ocean in particular seems to be aggressive. " Merlin nonchalantly shrugged and blew a hair strand out of his face.

 _" The ocean...?"_ Arthur repeated under his breath.

Gil was a siren, so he should be affected it as well...yet something told him, his friend was doing just fine. He was the exact opposite of all the other sirens, his appearance, and his character proved it, perhaps he should ask the blonde tomorrow...

" The full-moon forced your sister to stop her journey, but she should be here soon." 

" I see." Arthur replied.

Artoria, his twin sister also participated in a journey similar to his. They were unfortunately not allowed to train together, causing her to practice on a similar island, located in the east.

But from what he heard, she became a very skilled swordsman, to the point of being unbeatable, which only heightened his excitement of meeting her.

Not only would Arthur be able to see his sister again, he would also gain another sparring partner and a skilled one at that.

" I'll go to sleep now." Merlin slowly stood up, grabbing his staff next to him. " Old people such as I should rest at every opportunity." 

" You're not old." But his mentor didn't seem to quite hear him and left the library without bidding farewell.

" Really...The full-moon makes everyone go crazy, even _Merlin_." The prince muttered with a sigh.

He placed the book back into the shelf and gently extinguished the oil lamp, deciding to call it a day as well.

After all, today was _exhausting_ . As much as he adored his people, the opening ceremony simply didn't suit his tastes, it was too grand and extravagant. It was simply _too_ much and he was ashamed to admit that he sneaked out a bit earlier than intended, hoping to see a certain siren.

Which didn't work out in the end, sunset was too close for comfort and as much as he trusted Gil, he didn't trust the other creatures lurking in the depths of the sea, so tomorrow would have to do.

\---

" Seems like nothing is out of the ordinary over here..." Arthur gently quickened the pace of his horse and continued to glance through the thick bushes of the forest, making sure to keep a reasonable distance between him and the outer layer of it.

After every full-moon, it was a necessity to patrol every corner and curve of Camelot, making sure nothing extreme happened during the event. He was instructed to check the outer layer of the enchanted forest, a task that left a bitter taste in his mouth. The ocean was far more deadly, the men who had to patrol it were under constant danger, yet here he was tasked with something simple because he was the _prince_. 

A quiet rustle snapped him out of his thoughts, the sound was similar to footsteps, causing him to instinctively grab the hilt of his sword.

Arthur proceeded to slowly lead his horse towards the sound, silently releasing his sword from its sheath.

" Hello? Is someone there?" 

Silence, the little movements stopped for a second, before they erupted into a full sprint, without thinking, the prince jumped off his horse and followed the noise.

The forest was thick and difficult to navigate in, but he would be a failure of a knight if something of such a degree would stop him. Arthur pushed the thick branches with one swift movement away, tailing the sound with ease until the terrain promptly changed, leaving him alone in a small clearing.

" Huh...?" He glanced around his surroundings with a frown, the change was so swift, magic had to be involved.

He readied his stance for battle, this could be a trap or a magical being simply trying to hide his habitant, both were dangerous possibilities, he shouldn't have followed the sound like a fool...

There was a small pond in the middle of the clearing, the delicate lily pads appeared to be flawless to the point of making him wonder if the place was merely an illusion. He wasn't very proficient when it came to illusion magic, but he had seen Merlin do it often enough, so he had a vague idea if something was fake or not.

Arthur threw a small stone towards the pond and was startled to see it breach the water without any problems.

No illusion then, weird...The place gave off such an immaculate atmosphere, he was positive it had to be manmade.

With a frown, Arthur stepped closer to the pond, it was a lot deeper then he anticipated and with a yelp, he identified a shadow approaching from the deep. The sheer velocity of the shadow was too fast for a proper reaction and the prince was dragged into the water within seconds.

His first response was to get a hold of his surroundings, the pool was narrow but deep so whatever attacked him had to be under him.

Arthur observed the shadow and noticed a familiar golden gleam as a rather harsh ray of sunlight penetrated the water. 

_' Don't tell me...'_

With a powerful kick, the prince swam down the tunnel and met sly crimson eyes, the siren wasn't even trying to hide his haughtiness, causing Arthur to roll his eyes.

He slowly lifted his hands, holding Gil's face with care, never breaking eye contact with the other...and roughly pushed the siren's cheeks together.

The following reaction was honestly adorable, furrowed eyebrows, an unhappy hiss and slightly reddened, puffed cheeks.   
With a snarl, Gil left him alone underwater and glided towards the surface, the elegant movement of his fin was mesmerizing and Arthur could have watched it forever...if air wouldn’t have been a problem.

He quickly followed his friend and was met with a rather...unhappy siren.

" What the hell is wrong with you, you Mongrel?!" Gil hissed, his fin flicked with from side to the other an action he seemed to do a lot when he was irritated.

" Is that how you greet someone _dear_ to you?" It was said in such a sarcastic manner, Arthur doubted the siren truly realized the meaning behind those words.

" No, I don't." He gently took Gil's hand on his palm, the skin was as cold as he remembered, causing him to tighten his grip a bit. 

Even after all these years, Gil was still so _cold_ and he wasn't there to warm him up...

" This is how I greet people that I adore." Arthur pressed a delicate kiss on the smooth skin, he only planned for it to be a mere brush...yet something made him linger.

" Don't be ridiculous...you barely know me." The siren whispered.

" Then, let me get to know you better." 

The other's body tensed slightly until a small smile made its way upon Gil's face.

" You are a fool for befriending a siren."

" I a-." A splash of water interrupted him... _literally_. His companion challenged him with a smug smirk, his fin idly splashed the water around, occasionally causing the water to hit the prince's face.

" _Really_ , I never expected you to be so childish." Gil impassively raised his eyebrows, golden scales softly reflecting the sunlight with every movement.

" Hm, is th-Hah?!" Before he even got the chance to finish, Arthur practically pounced on him, knocking the air out of his gills with a huff.

The siren was now trapped between Arthur's body and a rock, the expression of the prince didn't suit him well _either,_ Gilgamesh tried to sway his tail around, but was met with _failure_.

" Caging a siren? You must be _deranged_."

" Hm, perhaps, but mocking a knight isn't very smart either." 

He felt two fingers circle his waist, the warmth they gave off sent a chilly shiver down his spine. The last time he had ever been touched by a human was _ten years_ ago, the feeling wasn't unpleasant just...very unique.

" What are you..." And that was when he felt it...fingers poking into his sides, starting to mercilessly tickle him. The feather-light sensation traveled through his entire body, causing him to awkwardly bend his back with a laugh.

" You're...r-ridiculous." Gilgamesh tried to free himself but found himself weakened from the onslaught of attacks and helplessly cried out after a particularly harsh jab.

" E-Enough!" Arthur finally backed off and sheepishly laughed.

" I apologize...I got carried away."

" Did you now?!" Gil bit back and tried to stabilize his breathing with a sigh, sides still throbbing from the attack.

" I didn't know you lived in the enchanted forest, Gil." The siren's ear fins slightly perked up at the name. 

" It's Gilgamesh." 

" Gilgamesh...?" Arthur repeated with a tilt of his head.

" When we were children I told you my full name, yet you were too incompetent to understand it." Gilgamesh scoffed, his cheeks slightly colored at the memory. Really, it was _him_ who was too inexperienced to pronounce his name, but could one judge him? He had no idea how the human language worked at that time! Even now, he sometimes struggled to release certain noises from his throat, but Arthur didn't have to know that.

" Do you wish for me to call you Gilgamesh then?"

" No..." The siren huffed, if the other started to call him by his full name _now_ , it would sound impersonal and he had to admit...he didn’t fancy the notion very well.

" Gil will do just fine."

" I see." Arthur gently smiled. " I'm glad, I prefer it this way as well."

The siren wordlessly agreed.

**Author's Note:**

> My twitter if anyone is interested : https://twitter.com/FrozenMoon5


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